The present invention relates to color measurement instruments, and more particularly to handheld color measurement instruments.
Color measurement instruments are capable of reading colors for the subsequent conversion of the colors to a mathematical representation. That representation can be processed using techniques known to those skilled in the art to perform color functions. Color measurement instruments include, by way of illustration and not limitation, spectrophotometers, colorimeters, densitometers, and spectroradiometers.
A handheld color measurement instrument is disclosed in U.S. Pat. No. 5,986,769 issued Nov. 16, 1999 to Krzyminski and entitled xe2x80x9cHand-Held Instrument for Reflection Measuring on Printed Sheets and Test Charts.xe2x80x9d This instrument is used in reading xe2x80x9ccolor barsxe2x80x9d on printed sheets. While providing a certain level of convenience and accuracy, this scanner is not without its drawbacks. First, the instrument requires a handheld rule to guide the instrument along a linear path. Second, the instrument appears to include a single photodetector. Third, the space required by the encoder wheel limits the positioning of the support wheels.
Color measurement instruments, especially the handheld type, have limited input devices. Typically, input is limited to a few keys, or even a single key. Consequently, such instruments are programmed and configured by (a) connecting the instrument to a personal computer (PC), for example, through a serial or USB connection, (b) inputting programming and configuring commands into the PC, and (3) communicating the commands from the PC to the instrument. Such an approach is more cumbersome and time-consuming than is desired by some operators of the instruments.
The aforementioned problems are overcome in the present invention wherein a handheld color measurement instrument is provided with improved functionality and ease of use.
In a first aspect of the invention, the instrument includes support rollers that guide movement of the instrument on a surface in a linear direction. The instrument includes a color measurement engine having an aperture opening through the bottom of the instrument. Consequently, the aperture scans along a line as the instrument is rolled over a surface such as a printed sheet.
In a first variation of the first aspect, the instrument housing includes line-defining elements for defining a visual line that is parallel to the linear direction of travel and that is aligned with the scanning aperture. The elements can be one or more of wings on the housing, notches in the housing, or lights supported by the housing. The line-defining elements assist in aligning the instrument with a target for accurate scanning.
In a second variation of the first aspect, the instrument is a densitometer including a blunt nose, and the scanning aperture is located proximate the nose. A plurality of photodetectors are arranged in an arcuate configuration about the scanning aperture. No photodetector is closer to the blunt nose than the scanning aperture. Consequently, the photodetectors do not interfere with placement of the aperture closely proximate the blunt nose of the instrument.
In a third variation of the first aspect, rolling support elements and an encoder wheel are mounted in the bottom of the instrument. The support wheels are proximate the perimeter of the bottom of the instrument. By separating the rolling support elements from one another as much as possible (i.e. positioning them proximate the perimeter of the bottom), the tracking of the instrument is improved. The encoder wheel is positioned interiorly of the support elements, where room is available for the entire encoder assembly.
In a fourth variation of the first aspect, the single color measurement engine within the instrument is capable of reading both barcodes and color bars or other targets. Consequently, the instrument can be used to read barcode information, for example, to configure the instrument. The instrument does not require a separate optical mechanism for reading the barcodes.
In a second aspect of the invention, the instrument can be programmed and/or configured by reading barcodes using the color measurement engine. More specifically, the instrument includes a housing, a color engine, and a control (e.g. a microprocessor) within the housing. The control is coupled to the engine and is capable of detecting and reading barcodes. Accordingly, programming and/or configuration information can be inputted into the instrument through barcodes. Such inputting is easy, accurate, and fast. When the instrument does not detect barcodes, the instrument performs color measurement functions (e.g. as described above).
These and other objects, advantages, and features of the invention will be more readily understood and appreciated by reference to the detailed description of the preferred embodiment and the drawings.